Variable speed pulley



Ja n. 19, 1943. l w. w.v HALLINAN 2,308,655

VARIABLE SPEED PULLEY Filed Jan. 13, 1940 4 Sheets-Sheet l y( 2l j l #57I 0 Y 3 5 22 i; '3.029 v i j 2 ,I l iff? j 27 l 36 g gli 55 m' Jal 19,1943 w. w. HALLINAN 2,308,655

VARIABLE SPEED PULLEY v Filed Jan. 1'5, 1940 4 Sheets-Sheet 2 f Je 2695Jan. 19, 1943. w. w. HALLINAN 2,308,655

VARIABLE SPEED PULLEY f v -Filed Jan.' 15. 1940 4 sheets-sheet s Jam'19, 1943- w. w. HALLINAN 2,308,655

VARIABLE SPEED PULLEY Filed Jan. 13. 1940 4 sheet-5.5mm 4 15 IZ 123 473T 4 147 Patented Jan. 19, 1943 Tas PATET ore The present inventionrelates to variable speed pulleys, and is particularly concerned withvariable speed pulleys controlled responsive to variations in pressureor temperature, and adapted to provide a continuously and uniformlyvarying change of speed if used as a driven or driving' member. A

The present application is a continuation-inpart of my priorapplication, Serial No. 196,003,

filed March 15, 1938, for Variable speed pulleys, Patent No. 2,210,976,issued August 13, 1940.

The variable speed pulleys constructed according to the presentinvention are capable of many A different applications. For example,they may be used for controlling the speed of a conveyor for conveyingarticles to be treated with heat, through a heated or drying atmosphere,or they may be used as a drive in a refrigerator system in which .thetemperature controls the speed of 'a compressor or a circulating fan.

One of the most important applications of my variable speed pulley as itnow appears to me is in the application of the pulley to thecirc-ulation of air in heating or air conditioning systems. For example,according tothe methods of the prior art, air conditioning systems arepro- This is not a desirable mode of operation.

One of the objects of the present invention is the provision of animproved variable speed pulley and heating system, in which thisintermittent action of the fan is eliminated, and in which it is notnecessary to operate the furnace at such a high bonnet temperature. Alowering of the operating temperature is less wasteful of fuel, and moreeconomical.

Another object of the invention is the provision of an improved variablespeed pulley and heating system, in which the furnace may be operated ata lower temperature and within a smaller range of temperature variationfor the purpose of maintaining a more uniform temperature in the spaceto be supplied with heated air,

'and in order to 'operate the system more efthe fan continues to operatebecause the fan vent the blowing of a blast of coldl air by thecirculating fan.

If the thermal control for the circulating fan motor is set atv a lowertemperature, the fan will start to operate before the bonnet of thefurnace has been heated to a sulcient temperature to heat the air whichiscirculated by the fan.

Under these conditions of the prior art I have found that the fan motorstarts and shuts on a number of times before it starts to run regularlyto circulate the air. For example, the fan may start and run for aminute or so and then shut off, for the reason that as soon as the fanmotor is started the cold air, which is brought in at the maximum pulleyspeed,cools oil the continues to use up the heat after the burner hasstopped.

According to the present invention, the operation of the air andcirculating fan is not wholly dependent upon the time of operation ofthe oil burner, as the air circulating fan may operate, depending uponthe temperature in the bonnet, or the temperature of the bonnet of thefurnace, and there is no tendency to over-run the temperature desired inthe rooms heated, because the speed of operation of the circulating fanis continuously varied with the bonnet temperature,

and diminishes as the temperature of the furfan speed is required to beset at a value which bonnet and thermal control and immediately shutsthe fan oil' again.

.ing load.

is sufllcient to take care of the maximum heat- I have also found thatair which is at a temlow seven perature of from 100 degrees F. to 110degrees F. still feels warm when it is circulating at a relatively lowspeed, and there is no cold air blast eilect in my heating system whichis operated under these conditions.

Therefore, another object of the invention is the provision of animproved heating system which is adapted to circulate the air at a speedand in a volume which is dependent upon the temperature of thecirculating air so that blasts of air which feel cold may be avoidedunder all conditions and so that the circulation of the air in thesystem may be accomplished for a longer period of time and more nearlycontinuously to avoid stratication, or what is called a at certain partslof the rooms which are being heated.

According to the present invention, with the improved thermallycontrolled variable speed pulley of my invention, the pulley may startat a slow speed, and the thermal control for the switch, which controlsthe fan motor, may be set relatively low. at, for example, from 100degrees F. to 110 degrees F.

Thisstill feels warm, as the fan is only moving a small volume of air,but as the furnace heats up and the temperature of the air in the bonnetincreases, the speed of the fan may be increased by the thermallycontrolled pulley, so that heated air is taken away more rapidly fromthe furnace and the heat produced by the burner is distributed morequickly when there is more heat to be distributed. f

Under these operating conditions the furnace may operate at a lowertemperature and there will be less heat lost in the cellar and less heatlost up the furnace stack. For example, suppose there is an upstairsdemand of from 5 t'o 10 degrees in the morning, as there might be, thisrequires a greater temperature at the bonnet of the furnace, and thebonnet temperature may go up to 150 or 165 degrees F. According to thepresent system, the blower speed is then automatically increased as thebonnet heats up.

Another object of the present invention is the provision of an improvedvariable speed pulley and heating system in which the speed of operationof the circulating fan is increased automatically to compensate for anyincreased filter resistance. The accomplishment of this result may beanalyzed as follows:

The heat input of the furnace may be assumed to be constant. and thetransfer effectiveness of the furnace, constant. Increased filterresistance, which is caused by filling up of the illter with dust orother foreign material, permits less air to pass through the filter andless heat is carried away from the bonnet. The furnace bonnet becomeshotter, and therefore the thermostat, which controls the pulleyaccording to the present invention, increases the effective diameter ofthe pulley, increases the speed of operation of the fan, and thusautomatically offsets the increased filter resistance by a higher fanspeed.

Another object of the invention is the provision of an improved heatingsystem in which the circulating fan may continue to circulate air at alow temperature continuously or almost concontrols of the prior art willturn the burner on several times and then turn it oif without the fanoperating. This is not eillcient because the heat which is producedduring this intermittent operation of the burner, without fan operation,is not conveyed to the rooms to be heated.

One partial solution of such a dlfiiculty would be the provision of atwo-speed motor system, but such two-speed motor systems would beexpensive and at best provide only a partial solution of the diiilculty.

Therefore, another object of the invention is i the provision of animproved thermally controlled variable speed pulley for heated aircirculating systems, which provides a substantially continuousmodulation of the fan speed, depending upon the temperature of the airto be circulated.

The volume of the blower increases with the square of the speed, and itis found that changes in volume may be made practically proportional tochanges in temperature so that the relation between volume andtemperature may be represented, for all practical purposes, as astraight line curve.

Another object of the invention is the provision of an improvedthermally controlled variable speed pulley which is adaptable to the useof standard commercial wafers and bellows, and which is provided with along bearing adapted to prevent tilting of the half pulley section whichmight 'cause the development of a rattle.

Another object of the invention is the provision of a thermostaticallycontrolled variable speed pulley in which the thermostat rotates axiallywith the pulley, in order to eliminate pressure connections betweenrotating and non-rotating parts, and in which thrust bearings may beeliminated.

Another object of the invention is the provision of an improvedthermostatically controlled pulley structure in which the thermostaticwafers are maintained in centered relation so that the complete pulleystructure is balanced, and in which abrasion and oxidation are preventedby non-metallic spacers between the wafers.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawings, in which similarreferences indicate similar parts throughout the several views.

Referring to the four sheets of drawings.

Fig. 1 is a diagrammatic illustration of a heating system embodying avariable speed pulley constructed according to the present invention;

Fig. 2 is an axial sectional view taken on'the plane which passesthrough the axis of the pulley shaft, with the thermostat in elevation;

Fig. 3 is 'a plan view taken from the top of Fig. 2: f

Fig. 4 is an end elevational view taken from the right end of Fig. 3;

Fig. 5 is an end elevational view of a modification in whichthermostatic wafers are employed; I

Fig. 6 is an axial sectional view taken on the plane of the line I-l ofFig. 7, looking in the direction of the arrows, showing the samemodiilcation:

Fig. 7 is a top plan view of the same modication, taken from the top ofFig. 6

Fig. 8 is an elevational view of another modiication. in which themovement between the pulley sections is controlled by bi-metallictherample, I have found that the Aheat anticipation4 75 mostats;

Fig. 9 is an end elevational view of a modication of Fig. 8;

Fig. 10 is a sectional view taken on the plane of the line lil-I3 ofFig. 8, looking in the direction of the arrows;

Fig. 1l is an elevational view of a modied form of a variable speedpulley in partial section showing the details of construction;

Fig. 12 is a sectional view taken on the plane of the line i2-i2 of Fig.11, looking in the direction of the arrows;

Fig. 13 is a fragmentary sectional view taken on the plane of the lineI3-I3 of Fig. l2, looking in the direction of the arrows;

Fig. 14 is an end elevational view taken from the right end of Fig. 11;

Fig. 15 is a sectional view taken on the plane of the line l-i of Fig.12.

Referring to Fig. 1, indicates diagrammatically a heating systemcomprising a hot air furnace 2l, provided with an outer housing 22,forming a plenum chamber 29, and provided with a bonnet 24.

The plenum chamber is connected with the rooms to be heated by the usualcold air ducts 25, which lead to the ventilation fan 26, preferably ofthe centrifugal type, and the outlet of the fan 2G is connected by acold air duct 21 to the plenum chamber 23.

Heated air is taken off from the bonnet 24 through a plurality of hotair ducts 23 leading to the rooms.

The centrifugal fan 26 includesrthe usual centrifugal impeller, mountedupon a shaft 29, the shaft being provided with a sectional V pulley 39,the sections of which may be spring pressed together to compensate forchanges in effective belt length, as the variable pulley 3i on the motor32 changes its effective diameter.

In other embodiments of the invention an ordinary fixed diameter Vpulley may be used at 3U, and the changes in effective length of the Vbelt 33 may be taken up by idlers or by a belt tensioning arrangement,such as the motor mounting, including the base 34 and support 35.

In the embodiment illustrated, the base 34 of the motor is pivotallymounted at 33 on the support 35 so that the weight of the motor tends tomaintain the belt 33 under suitable tension.

The motor shaft 31 is provided with a thermostatically controlledvariable diameter pulley, indicated in its entirety by the numeral 39. l

The thermostatic element'39 is subjected to heated air from the bonnet24 by means of a conduit 40, which extends from the bonnet 24, downwardto the thermostat 39, and discharges against thethermostat 39 at thedischarge opening 4i.

Other modes of making the thermostat responsive to the bonnettemperature comprise the use of thermostatic devices secured to themetal of the bonnet or placed inside of the bonnet, but the presentsystem is preferred because the motor may be substantially isolated fromthe hottest parts of the furnace and kept in a cooler condition.

The variable speed pulley 38 comprises a pair of movable pulley sections42 and 43, one of which, 42, is xedly secured to the motor shaft 31 by akey or a set screw 44 mounted in a threaded bore 45.

The motor is preferably a substantially constant speed motor which woulddrive the fan 26 at a substantially constant speed, irrespective oi witha centrally located cylindrical hub 49, having an axially extendingcylindrical bore 41 for receiving the motor shaft 31.

At the left endof Fig. 2, the pulley section may have a flat face 99,but on its right side and `outside of the hub 49 it is provided with afrustoconical surface 49, forming one side of a substantially v shapedgroove 53.

The pulley section' may comprise a member of similar material, having afrusto-conical surface 5I, sloping away from the frusto-conical surface49, so asto form the V shaped groove 93,' and having a fiatv annularsurface 52 surrounding the cylindrical hub 53.

The cy1mdrlca1 hub sa may be provided withy a cylindrical bore 54 forslidably receiving and engaging the outer cylindrical surface of the hub46 on the other pulley section.

The frusta-conical surface 39 and fiat surface 49 of the section 42 mayterminate in an annular ridge or at a cylindrical surface 55, at theperiphery of the pulley section t2. In a similar manner there may be acylindrical surface 56 at the periphery of the pulley section 43.

The hub 49 of the pulley section d2 may be provided with a pair ofoppositely located and diametrically extending threaded bores 5l, 58 forreceiving the screw .bolts 59, 60. These screw bolts may be utilized forsupporting a yoke Si, which may be of substantially U shape, having apair of legs t2, G3, joined by an end portion 64. The yoke..orthermostat-supporting member 6i -has a bore 65 in each of its legs S2,63 for receiving the screw bolts 59 and 60, whereby the yoke 9| isflxedly secured to the left pulley section. 42.

The hub 53 of the right pulley section is preferably provided with theaxially extending slots S6 for slidably receiving the legs 62, 63 of theyoke Si. The walls 61 and 68 of slot 66 have a suitable tolerance withrespect to the legs 62, 63 of the yoke 6l, to permit a sliding movement,and the pulley section 43 is thus slidably mounted on the hub of thepulley section 42, but any substantial amount of rotation is preventedbetween these pulley sections.

It will be noted that the hub 49 of the pulley section. is 'relativelylong, providing an elongated cylindrical bearing surface 46 for theouter hub 53, so that there is very little possibility of any tilting ofthe pulley section 43 on the pulley section 42, due to the action of Vbelt 69, which usually engages over slightly more or slightly less thanhalf of the pulley at one time'.

The belt 69, which has been termed a -V belt, is preferablysubstantially trapezoidal in section, being provided with the outercylindrical surface 10, inner cylindrical surface 1I, and lateralcylindrical surfaces 12 and 13.

The axial dimension between the frusto-conical surfaces 12 and 13 ispreferably relatively large so that these frusto-conical surfaces of thebelt may engage the surfaces 49 and 5I on the pulley sections over awider range of movement 0f the pulley.

The taper of the belt-engaging parts 49 and 5I of the pulley sectionsmakes the engaging surfaces farther apart at larger effective diameters,and the provision of a belt oi' suitable dimensions in an axialdirection permits the engagement of the belt with the Truste-conicalsurfaces on the pulley sections at greater effective diameters.

As such belts are customarily called V belts in the trade, I employ theterm V belt throughout this specication and claims to include not only abelt of actual V cross-section, but a belt of the type illustrated, inwhich the inner ridge o! the V has been eliminated, so that the belt isactually frusto-conical in cross-section.

The thermostatlc controlling device 39 may consistl of a metallicexpansible bellows, having one end closed by a metallic supporting platea, having a threaded supporting stud 1 la. The plate 10a has afluid-tight soldered or welded connection, with the end of the bellows12a, and the stud 1|a may have an axial illling aperture 13a, which maybe closed after iilling the bellows with a suitable expansible uld bymeans of a drop of solder 14a. In case it is desired to use the variablediameter pulley as a pressure responsive device, the conduit 11 maybeconnected by a suitable rotating uid-tight connection to a pipe leadingto a source of pressure to which the pulley is to be responsive, orleading to a thermostatic bulb arranged in proximity to the bonnet, orlocated inside the bonnet, or attached to the metal thereof.

Threaded stud 1|a extends through a centrally located aperture 15 in theyoke 6|, and the bellows is flxedly secured to the yoke 6| by a clampingnut 16 and a lock nut 11a. 'Ihus the right end of the bellows is xedlysecured to the pulley section 42 through the intermediary of the yoke 6|and the hub 48 and screw bolts 59.

The opposite end of the bellows 12a is closed by means of a metal plate18, which is likewise provided with a fluid-tight connection to theendmost fold of the bellows 12a, and the plate 18 is provided with apair of slots 19 and 80 for embracing the legs 62, 63 of the yoke 6I.

The plate is adapted to engage the annular end surface 8| of the hub 53of pulley section 43 so that expansion of the bellows 12a tends to forcethe pulley section 43 from lthe position of Fig. 2 toward that of Fig.3.

Thus a heating up of the expansble fluid in- `side the bellows 12a tendsto force the pulley sections together and to increase the effectivediameter of the pulley 3|. l

The yoke 6| may be provided with suitable permanent stops for limitingthe spreading of the pulley sections 42, 43 by having the ends of thelegs 62, 63 of reduced width to provide stop shoulders 82, 83. Thedevice may also be provided with suitable adjustable stop means,comprising a pair of sheet metal stop members 84, each of which areidentical in shape and which are slidably mounted on the screw bolts 59and 60 by means of slots 85.

Each of these stop members 84 comprises a substantially rectangularstrip of metal of the same width as the reduced width' portions 86 ofthe legs 62 and 63. The stop members 84 may have laterally extendingportions 81 at each side, provided with depending guide flanges 88 ateach side.

'I'he guide flanges 88 engage the sides of the legs 62, 63 and preventrotation of the stop member 84 on screw bolt 59. The left edges 89 (Fig.3) of the extensions 81 of th'e stop members 84 serve as stop surfacesfor engaging the annular surface 90 at the right side of the plate 1l inFig. 3. Thus the range of spread of the pulley sections 42 and 43 may beadjusted, and the device may be used with smaller belts, that is, beltsof less width in axial direction than that shown.

Referring to Figs. 5, 6, and 7, these are moditlcations in which certainadaptations and changes of structure may have been made for the purposeof accommodating the wafer type of thermostat.

In this embodiment the left hand pulley section 42 is substantially thesame, but the right hand pulley section 43 has its hub 9| of the samesize as the largest diameter of the pulley section. 'I'he hub 9| isformed by an axially projecting annular ilange, which is likewiseprovided with slots 66.

The yoke 9| has its end portion 64 of longer dimensions so as to spanthe relatively wide thermal wafers 92 and permit them to be arrangedbetween the legs of the yoke. The ends of the legs 82 and 63 arelikewise secured to the hub 46 oi' the pulley section 42 by the longerscrew bolts 93, which also pass through an annular member 94.

The annular member 94 may have flat end surfaces and an outercylindrical surface 95, and an inner bore 96 iitting on the hub 46.

The wafers 92 may be of any conventional or commercial construction, butare preferably formed with the centrally located partially Y sphericalprojection 91 at the center of one side,

and with a similarly shaped depression 98 at the center of the otherside. In order to retain the wafers 92 within the yoke 6|, the legs 62and 63 are preferably provided witli longitudinally extending slots 99,|00 for receiving the end portions |0| of a plurality of spacing andretaining plates |02. Each of these spacing plates may consist of asubstantially rectangular metal plate |02, formed with a presseddepression |03 at the center, which provides a protuberance on the otherside complementary to the depression in one side of the wafer.

In other words, the formation |03 at the center of each spacing andretaining plate-|02 is complementary to the formations 91 and 98 at thecenter of the wafers. Each spacing plate has an outwardly projectingange |04 at the opposite, sides of the plate, the iianges |04 beingadapted to be slidably received in the slots 99 and |00.

Thus the plates |02 are slidably mounted for axial movement inside theyoke 6|, and by virtue of the central depressions and protuberances onthe plates and wafers, the wafers are retained between the plates.

The wafers 92 are, of course, flexible metallic housings, the flexiblewalls of which are preferably corrugated, and the wafers are filled witha thermally expansible fluid, having a high' coefficient of thermalexpansion.

The endmost plate |05 at the left of the wafer assembly in Fig. 6 may bea circular plate of larger size than the wafers, and has a pair ofoppositely located slots |06 engaging on the opposite sides of the yokelegs 62, 63.

The opposite face |01 of the plate |05 engages the edge |08 of theannular hub 9| on the pulley section 43 and tends to urge the pulleysections together when the wafers expand, as shown in Fig. 7. The pulleysection 43 has a relatively long sliding bearing engagement between theinner cylindrical surface |09 and the outer cylinasoaas mostatic nementssecured to u at the center drical surface 36, and there is no tendencytoward tilting of the pulley section 43 relative to the pulley section42.

The operation of the embodiments sh'own in Figs. 2 to 7 is substantiallythe same. When the bellows or wafers are subjected to normal roomtemperatures or predetermined bonnet temperatures, the bellows are inthe contracted condition, as shown in Fig. 2, and the wafers are in thecontracted condition, as shown in Fig. 6.

The effective diameter of the variable speed pulley 3| is then at aminimum, and the sections 42, 43 of the pulley are automatically forcedapart by the action of the wedge-shaped belt 33, which is subjected totension by a suitable tensioning device or by'a tensioning weight of themotor mounting.

Upon heating up of the bellows 39 or wafers 92, these elements expandand tend to force the pulley sections 42, 43 closer together from theposition of Fig. 2 or Fig. 6 toward that of Fig. 3 or Fig, '7.

The effective pulley diameter is directly dependent upon the temperatureto which the thermostats are subjected, and the taper of thebelt-engaging surfaces on the pulley and the characteristics of thethermostats may be made such that the variation in speed issubstantially proportional to the variation in temperatureI by which Imean that the temperature speed relation may be expressed substantiallyas s, straight linel curve over a predetermined range of operation.

Upon a cooling down of the thermostat, th'e action of the belt and thebelt-tensioning arrangement tends to force the pulley sections apart tofollow up the contraction of the bellows or wafers, and the effectivediameter of the v pulley is at all times dependent upon the temperatureto which the thermostatic elements are subjected.

Each wafer has the center of its face preferably provided with aninsulating layer of nonmetallic material, adapted to prevent themetallic contact between the wafers 96 and the spacers |02. This layermay consist of a strip of zinc by means of a plurality of rivets II2,and the opposite ends of the bi-metallic elements may bear looselyagainst or be secured to a pressure plate I I3, which has its facesurface ||4 engaging the annular end surface |00 of the hub 9|.

The pressure plate ||3' is dished at ||4 to provide space for the rivetsH5, where rivets are used.

The thermostatic elements are preferably symmetrically arranged withrespect to the axis of the pulley and equally spaced from each otherangularly.

Referring to Figures 11 to 15, these views show a modification includinga specific structure which is provided with an improved mode oflubrication and an improved form of mounting the thermally responsivemeans on the pulley. In this embodiment the variable speed pulley,indicated in its entirety by the numeral |20, again includes the pair ofmovable pulley sections 42 and 43 and the pulley section 42 is againprovided with the centrally located cylindrical hub 46 having theaxially extending bore 41 for receiving the motor shaft 31. In thiscase, however, an arrangement is illustrated for adapting the bore toshafts of diiferent diameter, this arrangement including a metal sleeve|2| having an aperture |22 for the set screw 45 and the sleeve 2| fitsin the bore 41 and fits on the shaft 31.

This type of pulley is again provided with the v frusto-conicalsurface-49 forming one side of the substantially V-shaped belt groove50.

The pulley section 43 may comprise a substantially cylindrical metalbody |23 which has a oxide tape ||0- adhered to each side of the waferat the center depression and protuberance. I have found that this tapeprevents oxidation and wear of the wafers and keeps them in operatingcondition for long periods of time.

The present device may be provided with the same xed and adjustable stopmembers, and in order to prevent interference between the stop member 84and the spacer plates |02, the spacer plates have been provided with theend flanges lill mounted in slots 39.

Referring to Figs. 8 to l0, these .are views of another modification, inwhich the pulley sections may be of similar structure to that describedwith respect to Figs. 5 to 7. l

In this embodiment, however, the movable pulley section 43 is adapted tobe actuated by a plurality of bi-metallic thermostatic elements Thebi-metallic elements ||I may be of any conventional commercialconstruction, consisting preferably of two closely joined strips ofmetal of different coelcients of thermal expansion. The metal of thelarger coefficient of thermal expansion is arranged on the inside sothat the U-shaped bi-metallic thermostats tend to expand from theposition of Fig. 10 to that of Fig. 8.

In this Vembodiment thev supporting yoke 6| may have one end of each ofthe bi-rnetallic therhold a suitable amount of relatively viscouslubricant, which is supplied as needed to the external cylindricalsurface oi the hub 46.

The pulley section 43 is provided with an axially extending thrustflange |28 surrounding the hub 46 and adapted to engage a plate |29. Theiiange |28 is in the form of a sleeve having an axially extendingrectangular slot |30 at each side, the slots being diametricallyopposite to each other and the side walls i3! of the slot serving tolimit the rotative movement of the' pulley section 43 on the hub 46 bythe engagement of the shoulders |3| with the radial extending arms |32of a yoke |33.

The yoke |33 may comprise a substantially` rectangular metal frameformed of a strap of metal, the ends of which have been secured togetherto form the closed frame |33. The strap of which the frame |33 is madeis of uniform cross section, having a width which permits a slightclearance with respect to the walls |3| of the slots |30. The left end|34 of4 the yoke |33 is provided with a centrally located threaded bore|35 adapted to be engaged by a threaded screw bolt |36.

Hub 46 has its right end provided with a smaller bore |31 for passingthe screw bolt |36, the head of which is received in the bore 41. Hub 46also has on its fiat end surface |38 an axially extending cylindricallug |39 fitting in an aperture |40 in the frame |33. 'f

Thus the frame |33 may be fixedly secured to the end of the hub 46 bymeans of a screw bolt |36 which is driven home into the bore |31 and thelnterengagement of the lug |39 and the bore |40 prevents any relativerotation between the hub 46 and yoke |33. The yoke |33 slidably supportsa plurality of metal plates |4||44 which may be identical inconstruction, each plate being provided with a centrally located pressedball shaped protuberance |45. These pressed formations all extend in thesame direction and are substantially complementary to the ball shapeddepression |46 in one side of each thermostatic Wafer |41, and alsocomplementary to the projecting ball shaped formation |48 on the otherside of each thermostatic wafer. Each of the plates |4||44 as well asthe plate |29 has a rectangular slot |49 in each end.

'I'he walls |50 of these slots slidably engage the edges of the yoke |33and each wafer is disposed between two of the plates |29, |4||44. Theend Wafer at the right has its spherical projection disposed in anaperture located in the end wall of the yoke |33. Strips of adhesivetape may be interposed between the metallic surfaces of eachthermostaticwafer and the adjacent plates or frame which they engage.

In this embodiment it will be evident that the wedge-shaped belt 69 willtend to force the pulley sections 42 and 43 apart, the end of the sleeve|28 on pulley section 43 engaging the plate |29 and reacting against thestack of thermostatic wafers. 'I'he thermostatic wafers are maintainedin alignment by means of the plates |29, |4|- |44, and the yoke |33, andthese wafers are carried by the hub 46 through the yoke |33. When thethermostatic wafers expand, they react against the end of sleeve |28 onrpulley section 43 and tend to drive the pulley'sections together.

'I'hus an increase in the temperature of the thermostatic wafers drivesthe pulley sections together and increases the effective diameter of thepulley. A decrease in the temperature of the thermostatic wafers permitsthe wedgeshaped belt to drive the pulley sections apart and reduce theeffective diameter of the pulley.

The operation of the present variable speed pulleys in a heating systemof the type shown in Fig. 1 is as follows: When such pulleys areemployed, the critical operating bonnet temperature for the thermostaticdevice controlling the fanmotor 32 may be set at a lower temperature,such as, for example, 100 to 110 degrees. When the bonnet reaches thistemperature, the fan is turned on; but due to the fact that the parts ofthe pulley are in the position of Fig. 2, Fig. 6, or Fig. 10, theeffective diameterof the driving pulley is at a minimum, and the fanthus operated at a low speed, such as, for example, 275 R. P. M.

When the variable diameter pulley has its thermostatic element at ormore than maximum temperature so that parts of the pulley are in theposition shown in Fig. 3, the speed of rotation of the fan may be 500 R.P. M., for example. I desire it to be understood, however, that thespeeds which are given for examples are not in any sense limits forpractical use, as the fans speed may be made any desired value, and theexamples given are merely to show the range which has been foundeffective in exemplary installations.

Although the air in the bonnet is not at a high temperature, it stillfeels warm as it emerges from the registers when the fan is moving onlya small volume of air and at a low speed. Furthermore, the amount of airmoved through the plenum chamber of the furnace is not such that itcools the furnace down too quickly, and the fan will continue tooperatel instead of being turned off, as I have found to be the casewith the devices of the prior art.

In the arrangements of the prior art I have frequently noted that thefan operating at a maximum speed passes so much cold air through theplenum chamber that the temperature is so reduced that the fan is turnedolf again, This intermittent action is eliminated by my inven- 1 tion.

As the temperature of the air in the plenum chamber, and of course thatdischarged on the thermostat 39, by the duct 40, increases intemperature, the speed of the fan is automatically increased by theexpansion of the thermostat and the increase in the effective diameterof the driving pulley,

'Ihe present heating system permits a continu ous and gradual modulationof the fan speed so that the furnace may be operated at a lowertemperature vand fuel may be saved. 'I'he fan may be operated over alonger range of time, or it may be continuously operated at a lower rateof speed so as to avoid stratification and so as to constantly deliverheat from the furnace to the rooms by the moving air.

The speed varying effect of my thermostatically Vcontrolled pulley maybe accentuated by the use of a belt of constant length and by having.the driving and driven shafts at constant spacing, but by using asectional spring-actuated pulley on the driven member, for taking up theeffective length of the belt, which is increased or decreased, by theaction of the thermostatic pulley. Thus, one pulley would increase insize, while the other decreased, and vice versa, accentuating thespeed-changing effect of the thermostatically controlled pulley.

My thermostatically controlled pulley is adapted to be used either asthe driving or the driven member, and its thermostatic element may be soarranged that it increases the diameter or decreases the diameter uponincrease in temperature.

In addition to its use in a heating system as described, it may be usedfor controlling the speed of a conveyor for conveying articles through aheated atmosphere. Under such conditions, if the conveyor includes alarge number of painted articles, the temperature of theheatedatmosphere would naturally drop, due to the absorption of the heatby the articles, and to the increased evaporation of the solvents of thepaint.

Under these conditions, and with a decreased temperature, the conveyorshould move slower because the paint would require a longer time to dryat a lower temperature, and therefore the conveyor should keep thepainted articles on the conveyor a longer period of time.

The same would be true in the case of a baking oven, where my variablespeed pulley may be used for automatically compensating the conveyordrive for any drops of temperature. 'I'he variable speed pulley may alsobe used in driving the fuel feed of a Stoker, and it is of generalapplication wherever the speed-of drive may be advantageously variedresponsive to temperature or pressure.

While I have illustrated a preferred embodiment of my invention, manymodications may asoman be made without departing from the spirit ot theinvention, and I do not wish to be limited to the precise detalls ofconstruction set forth, butl desire to avail myself of all changeswithin the scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United lStates is:

l. In a variable diameter pulley, the combination of va pulley sectionadapted to be secured to a shaft or the like, with a second pulleysection slidably mounted on the rst pulley section in an axialdirection, said pulley sections being provided with opposedfrusto-conical surfaces adapted to form a pulley groove of wedge-shapedcross section, a supporting frame carried by one of said pulleysections, and whaving a part oppositely disposed to the other of saidpulley sections, and a plurality of thermostatic wafers in- -terposedbetween said opposing portionand the other of said sections, wherebyexpansion of the wafers is adapted to move one of said pulley sectionsrelative to the other to vary the eective diameter of the pulley groovewithrespect to a wedge-shaped belt of constant width, and a plurality ofslidable spacers carried by said frame and interposed between saidwafers, said wafers and spacers having interlocking depressions andprotuberances whereby the spacers retain the wafers within sa'id frame.

2. In a variable diameter pulley, the combination of a pulley sectionadapted to be secured to a shaft or the like, with a second pulleysection slidably mounted on the flrst pulley section in an axialdirection, said pulley sections being provided with opposedfrusto-conical surfaces adapted to form a pulley groove of wedge-shapedcross section, a supporting frame carried by one of said pulleysections, and having a part oppositely disposed to the other of saidpulley sections, anda plurality of thermostatic wafers interposedbetween said opposing portion and the other of said sections, wherebyexpansion of the wafers is adapted to move one of said pulley sectionsrelative to the other to vary the effective diameter of the pulleygroove with respect to a wedge-shaped belt of constant width, andnon-metallic insulating means interposed between said wafers forpreventing abrasion and oxidation of the engaging parts of said wafers.

3. A variable speed pulley comprising a hub and two relativelyadjustable members carried by said hub and forming the opposite sidewalls of an inwardly converging belt guide groove for receiving awedge-shaped belt by contact with said walls, one of said members beingxedly secured to the hub and the other of said members being slidablymounted on said hub, a substantially rectangular frame carried directlyby said hub, the other of said members having an axially projectingportion provided with grooves for receiving the inwardly and radiallyextending portions of said frame connected to said hub, thermallyresponsive means mounted in said frame and adapted to act on a pressureplate, said pressure plate engaging the axially extending portion ofsaid other member, whereby the members are adapted to be urged toward'each other to reduce the size of the groove and increase the eiectiveperiphery of the pulley upon an increase of temperature.

4. A variable speed pulley comprising a hub and two relativelyadjustable members carried by said hub and forming the opposite sidewalls of an inwardly converging belt guide groove for receiving awedge-shaped belt by contact with vsaid walls, one of said members beingflxedly semembers are adapted to be urged toward each other to reducethe size of the groove and increase the effective periphery of thepulley upon an increase of temperature, said thermally responsive meanscomprising a plurality of thermal wafers and said frame being providedwith means for retaining said thermal wafers in said frame.

5. A variable speed pulley comprising a hub and two relativelyadjustable members carried by said hub and forming the opposite sidewalls of an inwardly converging belt guide groove for receiving awedge-shaped belt by contact with said walls, one of said members beingflxedly secured to the hub and the other of said members being slidablymounted on said hub, a substantially rectangular frame carried directlyby said hub, the other of said members having an axially projectingportion provided with grooves for receiving the inwardly and radiallyextending portions of said frame connected to said hub, thermallyresponsive means mounted in said frame and adapted to act on a pressureplate, said pressure plate engaging the axially extending portion ofsaid other member, whereby the members are adapted to be urged towardeach other to reduce the size of the groove and increase the effectiveperiphery of the pulley upon an increase of temperature, and adjustablestop means carried by the opposite sides of said rectangular frame andadapted to engage said pressure plate to limit the spreading movement ofsaid members by engagement of said pressure plate with said stop means.

6. A variable speed pulley comprising a hub and two relativelyadjustable members carried by said hub and forming the opposite sidewalls of an inwardly converging belt guide groove for receiving awedge-shaped belt bycontact with said walls, one of said members beingilxedly secured to the hub and the other of said members being slidablymounted on said hub, a substantially rectangular frame carried directlyby said hub, the other of said members having an axially projectingportion provided with grooves for receiving the inwardly and radiallyextending portions of said frame connected to said hub, thermallyresponsive means mounted in said frame and adapted to act on a pressureplate, said pressure plate engaging the axially extending portion ofsaid other member, whereby the members are adapted to be urged towardeach other to reduce the size of the groove and increase the effectiveperiphery ofthe pulley upon an increase of temperature, said axiallyextending portion of said other member being provided with. an annulargroove and two annular flanges engaging saidk hub forming a reservoir,and lubricant absorbing means filling said reservoir and maintaining thelubrication of said hub.

7. A variable speed pulley comprising a hub and two relativelyadjustable members carried by said hub and forming the opposite sidewalls of an inwardly converging belt guide groove for receivingr awedge-shaped belt by contact with said walls, one oi said members beingxedly secured to the hub and the other of said members being slidablymounted on said hub, a substantially rectangular frame carried directlyby said hub, the other of said members having an axially projectingportion provided with grooves for receiving the inwardly and radiallyextending portions of said frame connected to said hub, thermallyresponsive means mounted in said frame and adapted to act on a pressureplate, said pressure plate engaging the axially extending portion ofsaid other member, whereby the members are adapted to be urged towardeach other to reduce the size of the groove and increase the effectiveperiphery of the pulley upon an increase of temperature, said hub beingprovided at its end with a, centrally located bore and threaded means insaid bore for securing said frame to said hub.

8. A variable speed pulley comprising a hub and two relativelyadjustable members carried by said hub and forming the opposite sideWalls of an inwardly converging belt guide groove for receiving awedge-shaped belt by contact with said walls, one of said members beingxedly secured .to the hub and the other of said members being slidablymounted on said hub, a substantially rectangular frame carried directlyby said hub, the other of said members having an axially projectingportion provided with grooves for receiving the inwardly and radiallyextending portions of said frame connected to said hub, thermallyresponsive` means mounted in said frame and adapted to act on a pressureplate, said pressure plate engaging the axially extending portion ofsaid other member, whereby the members are adapted to be urged towardeach other to reduce the size of the groove and increase the effectiveperiphery of the pulley upon an increase of temperature, said hub beingprovided at its end with a centrally located bore, threaded means insaid bore for securing said frame to said hub, and interlocking meanscarried by said hub and said frame cooperating with said threaded meansto' prevent rotation of the frame on said hub.

WILLIAM W. HALLINAN.

